William l



L. R. EMMET.'l SYSTEM 0F SHIP PROPULSION. APPLICATION FILED MAR. l5.|916v Patentd May 20, 1919.

Inventor: wnnamLREm et.,- @M2M His JtLor-neg 35 sion, of operating'fluidto the turbine, but

` etlicient operation bines,

varlationsof a ship WILLIAM I.. n Emmer, or scHENEcTAJJY, NEW

YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Taall who-m z't may concern:

i Be it lmown that I, WILLIAM L. R. EMMET, a Acitizen of the UnitedStates, residi at Schenectady, county of Schenectady, ISgtate of NewYork, have invented certain new'v and useful Improvements in Systems ofShip Propulsion, of which the following is a s peclication.

My invention relates to ship propulsion and in particular to systems ofship propulsion in which the ships propellers are driven directly orindirectly 'by elastic fluid tursuch as steam turbines. The object ofthe invention is to provide an` improved system of ship propulsion.Other objects of the invention will be pointed out in the course of thefollowing description.

The system of my present invention isparticularlyadapted fo'r use' onvessels Where efficient operation over two speed ranges must had, as,vfor example, over a high range ofspeeds and over alower range ofspeeds. In such ships, economic operation of the propelling apparatusmustlbe obtained over the desired range of high speeds,in cluding fullspeed, and alsop over .a suitable range of lower speeds, which I vwillterm the cruising speeds. The Apresent invention more particularlyrelates to systems of prof-- pulsion in which the prime-mover, such as asteam turbine,

is mechanically coupled,

either directly or through suit-able speed reducingumeans, to thepropeller shaft. Speed tem can be obtained by varying the admisover sucha wide range of speeds as would inclu-de both the high and cruisingspeeds of the ship cannot be satisactorily obtained merely by varyingthe steam admiion to the turbine, since if the turbine is designed andproportioned for high eiiiciency at its high speeds, `its etliciencywill be much poorer at' the relatively low speeds corresponding to thecruising speeds of the ship.

he power requiredlto propel a vessel A variesv approximately as the'cube of her speed, and, accordingly at cruising. speedsv lconsiderablyless than the maxlmum power o the propellingl equipment isrequiredrfordriving the ship, and greater economy could be obtained by using alsmall` highv pressure turbine operating at a higher speed in seriesr:interventor SHIP PnoPULsIoN.

Specification of Letters Patent.

Application med March i5, 191s. seria; No. 84,489.

.this turbine to the propeller shaft propelled by such a sys-' 'shaft'of the main turbine,

Patented May 20, 1919.

with. the main turbine, which latter in such a case would be used as alow. pressure turbine. The diiliculty in practically employlng such asystem lies in the fact thatl the full speed of the-main turbine is sohigh thatit is practically necessary toconnect ibyspeed reducing gearingoperation the s eed of the auxiliary turbine should be yas hlgh as thefull speed 'of the main turbine, a still greater speed reduction wouldbe necessary between the auxiliary turbine and the propeller'shaft if'this turbine 'is to drive the propeller at the lower cruising speeds.`'The aim of my present invention is to provide an improvedv arrangementof apparatus ina system in which two turbines are operated in series sothat the two turbines can operate at different speeds and deliver powertothe same shaft. In

another aspect the object of my invention is 75 and, since for economic`from the other, so as to establish a relation l .between the turbines bywhich'one operates at a higher speed than the other. t

'In carrying out my present inventlon I ...provide a main turbine,.directly or indirectly "coupled to a propeller shaft. This turbine. isdesignedv to elcientl drive the propeller at high speeds andisurthermore capable of economic operation when supplied with the exhauststeam" of anauxiliary or cruising turbine, which latter is operativelyconnected to the main turbine through an electromagnetic ldevice so asdriving the propeller. Thespeed relation of the cruisingand mainturbines when the exhaust ofthe former is mission of the latter is'established, within the limits of its electrodynamic capacity, by- `theelectromagnetic...device;`

form the electromagnetic device consists of an induction generatorhaving one of Its elements driven by the main turbine and the,`

other' by the auxiliary turbine and a synchronous motor having one. ofits elements stationary and the other with the armature elementsof thegenerator Vand motor electrically connected together to produce oppositedirections of phase rotation. The arto assist in supplied to the ad? Inits preferred Ioo mounted on. the

rangement of the apparatusin and the mode `of operation of the systemlof my presentA invention will ybe best understood from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

-Figure l is a diagrammatic representation of an electric system of shippropulsion embodying my present invention; and Fig. -2

diagrammatically illustrates a modified ar.- rangement of the propellingapparatus.

Referring first to Fig. 1 of the drawings, there is diagrainmaticallyrepresented a main elastic fluid turbine-5, such as a steam turbine,designed for high efiiciency as a high- Y speed high-pressure machineand adapted for economicalv operation at `a lower speed :when suppliedwith elastic fluid of la lower pressure@ r1`he'rnain turbine 5 ismechanically coupled -to a propeller shaft 6 upon which. is mounted a-lpropeller' 7*. For eiiicient operation the speed of the propeller shouldbe relatively much lower than the. Speed of the turbine 5, and,accordingly, it is generally necessary to Yinterpose suitableV speedreducing means, such vas the speed reducing gearing 8, betweenlthe'turlbine shaft and the propeller shaft. rThe gearing` 8 may consistofany suitable marine gearing, pref erably of the -elastic or flexibletype.

y Anauxiliary or cruising turbine 9, de signed for high-efficiency as ahigh-speed high-pressure machine, has its exhaust 10 communicating withthe admission pipe'll i main turbine 5 receives steam directly from theboilers, and its exhaust 19 may be connected'to a suitable condenser`aswell understood. Under' this condition of opera tion the main turbineruns at its high speeds with high eiiiciency. If valves 16 and 18 areopen and valve 17 closed ,the auxiliary turbine 9 reeives steam directlyfrom the boiliersand exhausts into the admission of the main turbine.`Under this Kcondition the auxiliary turbine is adapted to operateX at ahigher speed than. the -main turbine, .but at the same time the drivingof the main turbine at a relatively low speed with relatively lowpressure steamvisy economical'.

An electromagnetic device comprlsing a polyphase induction machine A anda polyis employed for operatively connecting 'the cruising tur` 'bine tothe main turbine. Thefi'ield magnet structure 20 of (theinductioninachineis of the overhung type and is keyed to the shaft ofthe ,auxiliaryl turbine 9 whereby it is phase fsynchronous machineadapted to` be rotated by the cruising turi bine.

machine may be a squirrel cage winding 2l,

The eldwinding of the induction as is well understood inthe art. Thearmature core .22 ofthe induction machine is mounted on the shaft `ofthe main turbine 5. The armature core -23 ofthe synchronous machine B isalso" mounted on theshaft of the main turbine 5, while the field magnetstructure 24 of the synchronousmachine is stationary. The field' winding25 of the syn- `chronous machine is adapted to be supplied with directcurrent from any suitable source,

such as the D. C. mains 26, and a suitable switch 27 is employed vforcontrollin'gthe excitation of the synchronous machine The polyphasearmature winding 28 of the induction machine A is electrically connectedto the polyphase armature winding 29 of' the synchronous machine .Bmeans of conductors 30 extending through an axial l hole the shaft uponwhich the cores 22 and 23 are mounted. The windings 28 and 29 areelectrically so vconnected as to-pro duce opposite ydirections of phaserotation. The operation of the /system of Fig. 1 is tions of the ship,the switch -27 is open, valves 16. and 18 are closed, and valve 17 isopen. LiveI steam is thus admitted to the main turbine 5, which,accordingly, operates at its high speed thereby driving the propeller 7at such a speed as is required for navigating the ship at high` speed.During this condition of operation the auxiliary turbine 9 is idle andthe iield magnet structure 20'of the induction machine remains at rest.

' as follows :.-For full and high speedwoperat Speed variations of thepropeller and hence I of the ship for this condition of operation can beobtained by controlling the admission rof steam to the turbine 5, andfor this purpose a valve/10 is included in the main suplos ply pipe 12.Theyalve 4:0 is designed to be' i operatively connected to a -s eedgovernor on the main' turbine 5 and to a suitable speed control lever,substantially as described in my 1,137,308, dated Apr. 27, `1915.

For the navigation of theship atrela tively lower speeds, such as hercruising speeds, 1,an arrangement ofthe propelling apparatus is made bywhich 'the operating speed of the mainvturbine 5 is materially reduced.Y This condition of operation is obtained by closin the switch 27 andvalve 17 ,l

and opening va ves 16 and 18, whereby the U. S.' Letters 'Patent Nmfield bf the synchronous machinefB is en- `f ergized and highpressure-steam is admitted directly. ,tejthe cruising turbinel 9,. whilethe main turbine 5 operates with exhaust steam received from thecruising` turbine. relative speeds of 'the turbines 5 and 9 will dependupon thedesign of theelectri/cal machines A and B, and in particularupon the rati-o of the number of' poles of these ma= chines. This willperhaps be better understood by considering for the moment the inductionmachine A as a motor supplied with electric energy from .the synchronousmachine B. The induction machine will then run' up to a 'speed slightlybelow its synchronous speed, which means that the rotatable field magnetstructure 20 will rotate at a speed equal to the speed of its rotating'prlmary core 22 plus the synchronous speed of the induction machineminus its slip. If livesteam is now supplied to the auxiliary turbine 9until it acts as a prime-mover and drives the rotatable field magnetstructure 20, the actual speed of the latter will increase to a valueslightly above its synchronous speed plus the speed of' the rotatingcore 22, and consequently the induction machine will cease to act as amotor and will olperate as a generator delivering energy to t esynchronous machine' B, which latter now runs as a motor and assists indriving the shaft of the main fturbine 5. The induction generator Areceives its excitation from the synchronous machine B` as is Wellunderstood in the art.

The relative speeds of the two turbines are thus established by theelectrical rela- A tions of the two machines A and B, within theelectrodyn'amicl capacity of the latter machines, and thus the turbine9. rotates at a speed equal to the synchronous speed of the inductionmachine A plus its slip faster than the main turbine 5. The design ofthe electrical apparatus and of the turbines in Athe equipmentillustrated in the accompanying drawings may for the purposes of ex`planation Ibe assumed to' be such that the 'main turbine 5 runsw underthis condition of operation at a speed substantially one-half its :fullspeed under the o ment first described, but slnce the turbine 5 receivessteam of a relatively low pressure from -the exhaust ofthe auxiliaryturbine its operation at this lowerspeed is economical. The cruisingturbine will, accordingly, operate at substantially double the speedofthe main turbine plus the slip of the induction machine. With a highspeed main turbine such as would be used ina vessel propelled throughgearing, this doubling of the speed affords anamply high speed foradvantal geous design of the cruislng turbine which 1s intended to giveits best results when the vessel is running at relatively low speeds.

The same objects can obviously be accomplished by different arrangementsof the apparatus of the system, although the arrangement shown in Fig. lis now deemed to be the preferable form for most cases. The

induction machine and synchronous machine can, if desired, be placed onoppositeends of the main turbine and can be electrically -connectedtogether, etheraxially through the shaft or by means of collector ringsand v sponsive device of the erating arrangepleads. Such an arrangementof the apparatus is diagrammatically represented in Fig. 2 or" theaccompan ing drawings. In Fig. 2 the induction machine A is ositionedbetween the auxiliary tunbine 9 an the main turbine 5', while thesynchronous machine B is positioned between the main turbine 5 and ingelements of the systems of Figs. l and 2 are designated by the samereference numerals. It will further be understood that the relativepositions of the armature and field elements of either orboth of themachines A and B can be reversed if any conditionsrender such reversaldesirable. The particular arrangements shownv in the accompany-ingdrawings avoid moving contacts and are, therefore, esirable for mostcases.

In Figs. l and 2 of the drawings I have shown a valve 41 included in theadmission pipe of theauxiliarv turbine 9. This valve is adapted to beconnected to a speed respeed gavernr type on the auxiliary turbine 9,substantially as described in my U. S. Letters Patent N 0.

` 1,137,593, dated Apr. 27, 1915. The valve 4l thus operates to limitthe speed of the auxiliary turbine without shutting the turbine down.The valve 40 is operated, as previously described, to adjust theadmission 0f steam to the main turbine, or to the auxiliary turbine,depending upon the arrangement of the apparatus, or obtaining variationsof the ships speed over both her high and cruising speed ranges.Adjustment of the valve 40 thus serves to vary the speed of lthe mainturbine when the apparatus is arranged for the high speed range and ofboth turbines when the apparatus is ar'- ranged for the lower range ofspeeds. As the speed ofthe ship is increased from her cruising speed byincreasing the'steam admission to the auxiliary turblne the action ofthe latter 'becomes less effective and at any desired point the fullspeed connections can be made by opening switch 27, openin valve thespeed reducing gearing 8. Correspond- 17 and closing valves 16 and 18. Tis can p art from the foregoing description and exi planation. ,Theelectromagnetic device consistingof the induction and synchronousmachines establishes such a relation' between the turbines that they canrun at different speeds and deliver power in conjunction to thepropeller shaft. Since the relative speeds of the two turbinesh areestablished by the electromagnetic device, within the limits of thelatters electrodynamic capacity, this relation can Aobviously be variedby varying the design of the device, as, for cxample,`by

changing the ratio of the pole numbers of the induction and .synchronousmachines. Where the design of the apparatus is such that` the cruisingturbine runs at substantially twice the speed of the main turbine,substantially one-half ofl the power of the auxiliary turbine isconverted into electric energy, ywhile the other half of the power of-this turbine is delivered direct to the main turbine shaft through thetorquel of the induction generator. The power of the auxiliary turbinewhich is converted into electric energy by the induction v^generator isalso delivered to the shaft ofthe main turbine by the synchronous motor.Since only onehalf of the total power of the auxiliary tur-y bine isturned into electric energy, the size ofthe motor-generator combinationneed be only a'bout one-half what it would have to be if all of thepower ofthe auxiliary turbine were converted into electric energy anddelivered to the propeller shaft, and hence the electrical losses areonly about half as great as they would be in -the latter case.

v It will of course be understood that the relaelastic fluid turbinehaust into said main turbine, an electric generator lhaving tworotatable elements, oneof which is adapted to be driven by the mainturbine and the other-by the auxiliary turbine, an electric motor havingtwp elements one ofwhich is stationary and the other is connected tosaid main turbine, and means electricalyly connecting said motor to saideneraton '2. system of ship propulsion comprising a propeller, a mainelastic uid turbine coupledl to. 4said propeller, an, auxiliary elasticfluid turbine arrangedv to vexhaust into said main turbine, analternating current dynamo-electric machine 'havin two rotatableelements one of which-is a apted to be'driven by the main turbine andthe other by .theauxiliary turbine, a second alternatingl currentdynamo-electric machine having two elements one of -which is stationary`and the other connected 'to said lmain turbine, andmeans electricallyconnectmg said dynamo-electric machines so 3. A system of shippropulsion comprising apropeller, a main elastic fluid turbine coupledto said propeller, an auxiliary elastic iiuid turbine arranged toexhaust into vsaid main turbine, an alternating current generator havingtwo rotatable elements one of which is adapted to be driven by the mainturbine and the other by the auxiliary turbine, an alternating currentmotor having two elements one of which is stationary and the other isrotatable and connected to said main turbine, and means electricallyconnecting the rotatable element of said motor to said generator.

' 4. Afsystem of ship propulsion compris;-

ing a propeller, a main elastic iuid turbine 'coupled to said propeller,an auxiliary elas-` tic fluid turbine arranged to exhaust into said mainturbine, an alternating current induction generator having two rotatableelements one of which is adapted to be driven by the main turbine andthe other by the auxiliary turbine, an alternating current synchronousmotor having two,` elements one of which isstationary land the other isconnected to said main turbine, and means electrically connecting saidmotor to said generator so that the motor assists in driving thepropeller.

5. A system of ship propulsion comprising Va propeller, a\main elasticfluid turbine coupled to said propeller, an auxiliary elastic fluidturbine larranged to exhaust into said main turbine, a dynamo-electricmachine having two rotatable elements one of which is adapted to bedriven bythe main `turbine and the other by the auxiliarytur-- bine, asecond dynamo-electric machine having two elements one of which isstationary and the other is connected to one ofv said turbines, andmeans electrically connecting said dynamo-electric machines so that oneof said machines operates. as a, generator and supplies electric energyto the other machine whereby. the latter machine operates as a motor andassists in driving the propeller.

6. A system of ship propulsion comprising a propeller, a main elasticHuid turbine coupled to` said propeller, an auxiliary elastic fluidturbine arranged to exhaust into said main turbine, and anelectromagnetic device operatively connecting said turbines to` getherand adapted to establish -a lrelation between the turbines whereby theauxiliary turbine operates at a higher speed than the main turbine.

7. A system of'ship propulsion comprising a propeller, a main elasticfluid turbine coupled to said propeller, an auxiliary elastic Huidturbine arranged to exhaust into said main turbine, and anelectromagnetic I ing a propeller, a main elastic fluid 'turbine devicecomprising an alternating current generator and an alternating currentmotor operatively connecting said turbines -to'- gether and adapted toestablish a relation between the turbines whereby theauxiliary turbineoperates at a higher speed, than the main turbine. i

8. A system of ship propulsion compriscoupled to said propeller, anauxiliary elastic fluid turbine arranged fto exhaust into said mainturbine, and an electromagnetic device-operatively connectin saidturbines togetherand adapted to esta lish a relation between theturbines whereby the auxiliary turbine operates at a higher speed thanthe main turbine, said electromagnetic device comprising an alternatingcurrent induction machine and an alternating current synchronous machineelectrically connected together so that one of said machines operates asa generator and supplies electric energy to the other machine wherebythe latter machine operates as a motor and assists in driving thepropeller.

9. A system of ship propulsion comprising a propeller, a main elasticfluid turbine coupled to said propeller, an auxiliary elastic fluidturbine arranged; to exhaust into said main turbine, a polyphasealternating current dynamo-electric machine having two rotatableelements one of which is adapted to be driven by the main turbine andthe other by the auxiliary turbine, a second polyphase alternatingcurrent dynamo-electric machine having two elements one of which isstationary and the'other is rotatable and .connected to said mainturbine,

and means electrically connecting said dynamo-electric machines to giverelatively opposite directions of .phase rotation and so that one ofsaid machines operates as a generator and supplies electric energy tothe other machine which operates as a motor and assists in driving thepropeller. l 10. A, system of ship propulsion comprising a propeller, amain elastic fluid turbine coupled to said propeller, an auxiliaryelastic fluid turbine arranged to exhaust into said main turbine, analternating current Vinduction generator havin two rotatable elementsone of which Ais a apted to be driven by the main turbine and the otherby the auxiliary turbine, an alternating current synchronous motorhaving two elements one of which is stationary and the other isconnected to said main turbine, and means electrically connecting saidmotor to said generator so that a substantial part of the power of saidauxiliary turbine is converted into electric energy by said generatorand delivered by said motor to the shaft of said main turbine.

ll. A system of ship propulsion comprising a propeller, a main elasticfluid turbine coupled to said propeller, an auxiliary elastic fluidturbine arrangedA to exhaust into said main turbine, and electromagneticmeans operatively connecting said auxiliary turbine to said mainturbine, said electromagnetic means comprising two dynamoelectricmachines electrically connected t0- gether so that a substantial part ofthe power of said auxiliary turbine is converted into electrical energyby one of said machines and delivered by the other of said machines tothe shaft of said main turbine.

' 12. A system of ship propulsion comprising a propeller, a main elasticfluid turbine couple-d to said propeller, an auxiliary elastic fluidturbine arranged to exhaust -into said main turbine, an alternatingcurrent dynamo-electric machine having two rotatable elements one ofwhich is adapted to be driven by the auxiliary turbine, a secondalternating current dynamo-electric machine having two elements one ofwhich is stationary, the second element of each of said dynamo-electricmachines being mounted on the shaft of said main turbine, `and meanselectrically connecting said dynamo-electric machines together so that`a substantial part of the power of said auxiliary turbine is converted'into electric energy by one of said `machines and delivered by theother of said WILLIAM L. n. EMMET.

